Non-Equivalent Cmax BE, Hybrid Approval from Global regulatory authorities
Client: UK based pharmaceutical company
Product: oral immediate and fast absorption solution vs. gastro-resistant capsules/ODT
Pathway: Global regulatory authority hybrid application
The Challenge
Early pharmacokinetic testing showed the client's oral suspension matched the reference capsule on total drug exposure (AUC), but not on peak concentration (Cmax) — an outcome driven by the fundamental difference between an immediate-release liquid and a gastro-resistant capsule, not a manufacturing or quality issue. Standard bioequivalence rules would have blocked approval.
Our Approach
- Proactively engaged Global regulatory authority for scientific advice before running the pivotal study, rather than reacting to a failed result
- Designed a therapeutic equivalence study pairing 24-hour intragastric pH monitoring with plasma PK sampling in healthy volunteers
- Built the scientific case on the established mechanism of proton pump inhibitors: acid suppression tracks with total exposure (AUC), not peak levels — supported by 50+ published studies and precedent from other Global regulatory authority-approved products with the same profile
The Outcome
- Proactively engaged Global regulatory authority for scientific advice before running the pivotal study, rather than reacting to a failed result
- Gastric acid suppression statistically equivalent between the two products
- No safety signals; only mild, self-resolving adverse events
- Hybrid application successfully supported despite Cmax falling outside standard limits
Key Study Results
The study demonstrated the following key findings.
| Metric | Result | Standard Range |
|---|---|---|
| AUC (extent of exposure) | T/R ratio 92.7% | 80–125% (met) |
| Gastric pH suppression (Day 1) | Statistically equivalent (p = 0.31–0.35) | Non-significant difference required |
| Cmax (peak concentration) | 136% of reference | Outside standard 80–125% window |
| Safety | 5 mild, self-resolving events; no serious AEs | - |
Why It Matters
This case demonstrates a proactive, science-led regulatory strategy: spotting a PK mismatch early, engaging regulators ahead of time, and building a robust pharmacodynamic case turning what could have been a rejected submission into a defensible, approved pathway.
Securing Agreement on a Novel Reference-Product Strategy for a First-in-Class Implant
Client: UK based pharmaceutical company
Product: Sterile subcutaneous pellets
Pathway: Global regulatory authority scientific advice, supporting a well-established-use marketing authorisation application
The Challenge
No subcutaneous pellet product holds regulatory approval anywhere in the regulated market, so there was no existing reference product to benchmark against, normally a precondition for a bioequivalence-based application. Without a scientifically defensible comparator, the standard regulatory route wasn't available.
Our Approach
- Identified and justified a cross-route surrogate reference product an established intramuscular depot injection based on shared depot pharmacokinetics (sustained release, avoidance of first-pass hepatic metabolism), even though its dosing interval and administration route differed from the pellet
- Designed a multiple-dose, steady-state crossover bioequivalence study addressing the specific technical challenges of long-acting implants: delayed onset, high peak-to-trough fluctuation, and multiphasic release
- Proactively brought the reference-product rationale, study design, and bioequivalence criteria to the Global regulatory authority for scientific advice before committing to a pivotal study rather than risking rejection after the fact
The Outcome
- Global regulatory authority agreed the proposed surrogate reference product and bridging rationale were scientifically acceptable
- The proposed steady-state crossover study design was confirmed as fit for purpose for this class of long-acting implant
- The applicant is now cleared to proceed to the pivotal bioequivalence study on this agreed basis a critical unblock for a product class with no existing regulatory precedent in the Regulatory authority
Why It Matters
This case shows how early, structured engagement with regulators can unlock a viable pathway for genuinely novel products where no direct precedent or comparator exists. By building the scientific justification up front and testing it with the regulator before committing resources to a pivotal trial, the client avoided the risk of a late-stage rejection on study design grounds.